1. Field of the Invention
This invention generally relates to the forming chamber for the formation of glass on a molten metal. In particular the invention relates to the repair of the bottom refractories of the forming chamber.
2. Discussion of the Prior Art
In processes of float glass formation wherein molten glass is formed into sheets on a pool of molten metal there has been a continuing interest in methods of repair of refractories in the forming chamber. As illustrated in U.S. Pat. No. 3,594,147 to Galey et al the bottom refractories of the forming chamber may be cast in place. In the most common type of bath bottom construction as illustrated by U.S. Pat. No. 3,584,477 to Hainsfurther, the bottom blocks are precast, layed in place and bolted down. The refractory blocks must be held down or they will float upward onto the surface of the metal bath. The tin which ordinarily forms the molten metal of the bath is corrosive to steel and leaks will result if the metal casing of the bath is exposed to continual attack of the molten metal. Further, if the studs holding the refractory blocks are exposed to molten metal they will corrode and the blocks will float to the surface of the bath.
The view of the difficulties that are caused by the failure of bottom refractories in the bath, there is a continuing need for a method for repairing such refractories without the need to shut down and drain the forming chamber. For reasons not entirely understood, there is a tendency for the bottom refractories, particularly in bolted down precast blocks, in the forming chamber to delaminate at a point about 7" from the upper surface of the blocks. The typical refractory bottom block of a forming chamber is about a foot thick. The delamination of the upper portion risks exposure of the hold down bolts or studs, which if they are corroded lead to the entire block floating to the surface and exposing the metal casing of the forming chamber to attack by the tin. Therefore, when delamination occurs it must be repaired within a short time. The normal method of repair prior to the instant invention was to shut down the forming chamber, drain the metal from the bath, and reset or recast a new block or blocks where delamination has occurred. This, of course, is very expensive as extensive delays in production are caused. Also, it has been known in the glass industry that baths were not repaired but continued to run after the bottom had deteriorated such that a release of tin through the bottom occurred. Also, operation with exposed bottom steel can cause glass bubble defects. Therefore, there is a need for a reliable method of in situ, hot repair of the bottom refractories in a float forming chamber. There is a need for a repair that may be done through the molten metal without draining the forming chamber.